title: Temporal lobe surgery in medically refractory epilepsy: a comparison between populations based on MRI findings.
abstract: BACKGROUND
  High resolution MRI findings suggestive of mesial temporal sclerosis (MRI-MTS) correlate with good outcome after surgery. However, a large group of patients present with normal brain MRI (N-MRI) and temporal lobe epilepsy (TLE). We aim to compare pre-operative ictal EEG patterns in predicting surgical outcomes in the population with MRI-MTS vs. N-MRI after selective anterior-mesial temporal lobe (AMTL) resection.
  
  
  METHODS
  241 patients with unilateral anterior ictal EEG findings underwent selective AMTL resection. 143 MRI-MTS and 98 N-MRI patients were identified. Outcome was based on the modified Engel classification, ictal EEG pattern at seizure onset, demographics and MRI findings.
  
  
  RESULTS
  Seizure-free outcome was seen in the MRI-MTS in 79% of patients, compared to 59.1% (p<.005) of the N-MRI group. No significant difference was identified in ictal EEG patterns at presentation between groups. Class I outcome was achieved in 78.9% of patients that had theta rhythm and MRI-MTS compared to 57.9% of patients that had theta rhythm and N-MRI (p<0.05).
  
  
  CONCLUSIONS
  Surgical treatment for mesial TLE is effective. Positive MRI suggestive of mesial temporal sclerosis (MTS) predicts better seizure control after surgery. Theta rhythm is the most common ictal pattern and seems to carry the best prognosis for TLE. However, a well-selected group of patients with N-MRI will benefit from surgical intervention, and similar outcome to MRI-MTS patients can be achieved if delta ictal EEG pattern is presented at initial onset. Early referral to an epilepsy center cannot be emphasized enough, even in situations when high-resolution brain MRI is normal.
authors.affiliation: Department of Neurosurgery and Brain Repair, Morsani College of Medicine, University of South Florida, Tampa, United States.
authors.forename: Tsz
authors.initials: T
authors.lastname: Lau
authors.affiliation: Department of Neurosurgery and Brain Repair, Morsani College of Medicine, University of South Florida, Tampa, United States.
authors.forename: Timothy
authors.initials: T
authors.lastname: Miller
authors.affiliation: Department of Neurosurgery and Brain Repair, Morsani College of Medicine, University of South Florida, Tampa, United States.
authors.forename: Travis
authors.initials: T
authors.lastname: Klein
authors.affiliation: Department of Neurology, Morsani College of Medicine, University of South Florida, Tampa, United States.
authors.forename: Selim R
authors.initials: SR
authors.lastname: Benbadis
authors.affiliation: Department of Neurosurgery and Brain Repair, Morsani College of Medicine, University of South Florida, Tampa, United States. Electronic address: fvale@health.usf.edu.
authors.forename: Fernando L
authors.initials: FL
authors.lastname: Vale
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D004569:Electroencephalography / Q000379:methods; D004833:Epilepsy, Temporal Lobe / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods / Q000592:standards*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012598:Sclerosis / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery; D016896:Treatment Outcome; D055815:Young Adult
keywords: AMTL; Epilepsy surgery; Ictal EEG; MRI-MTS; MTLE; MTS; N-MRI; Negative MRI; Nonlesional; Outcomes; TLE; Temporal lobe; anterior mesial temporal lobe; mesial temporal lobe epilepsy; mesial temporal sclerosis; mesial temporal sclerosis positive MRI; normal MRI; temporal lobe epilepsy